1. Field of the Invention
The present invention generally relates to cameras and, more particularly, to a camera in which an electronic flash is energized to radiate an object with a light radiated therefrom to thereby take a picture of the object.
2. Description of the Related Art
In conventional cameras, such as a so-called single-lens reflex camera or the like in which a focal length of a lens is varied when a picture of an object is taken, there is employed a method in which a sensor or the like is disposed on the outside of a main optical system and an amount of light to be produced from an electronic flash is controlled on the basis of a detected value from the sensor.
When the above control method is employed, the amount of light from the electronic flash cannot be adjusted properly because the radiation angle and radiation range of the electronic flash are varied depending upon the focal length.
To avoid the above disadvantage of the conventional method, a light reading method known as a direct light reading method has been adopted recently.
According to the direct light reading method, when the electronic flash is energized, a reflected light from the surface of a film is read by a sensor and an amount of light radiated from the electronic flash is controlled on the basis of the measured result of the light reading.
When the amount of light from the electronic flash is controlled according to the direct light reading method, a plurality of direct light reading elements are required. Therefore, the control unit of the electronic flash cannot be substantially mounted on a camera since a sensor that measures an amount of light radiated from an electronic flash cannot be disposed on the optical system thereof from a physical standpoint.
In a camera such as an electronic still camera which utilizes CCD (charge-coupled device) elements instead of a film, the main optical system has no plane on which an incident light is irregularly reflected. Also, a proper light reading element cannot substantially be disposed outside the range of the condenser lens system.
Further, since most of the CCD elements have a small image size as compared with the film, the focal length of the equivalent lens can be reduced, thus making it impossible to keep a space in which an element that converges a reflected light from a picked-up object is disposed.
Furthermore, even when a light that was irregularly reflected on the film surface is read, the light thus irregularly reflected on the film surface can be converged at the position distant from the film surface, thereby making it difficult to effect a so-called spot light reading and a so-called split light reading.
Consequently, when a parallax with the electronic flash and the radiation angle of the electronic flash are corrected or when the amount of light from the electronic flash is controlled momentarily, a fine control such as a logical judgement, a comparison with a value read by a main light reading system without light emission or the like, cannot be effected. Therefore, a satisfactory flashlight photography cannot be effected.